so what about those who do? i can't imagine these guidelines are relevant to them necessarily? >> correct, katie, they do not apply to women at high risk. so women with a strong family history should talk to their doctor about which screening tests are best for them. >> couric: so now women and their doctors are going to be quite conflicted about this, aren't they? >> they are, katie, and it's going to stem up a lot of anger and confusion. as a medical professional i can understand the statistical thinking behind these recommendations but as a doctor who has many young women who have been diagnosed with breast cancer by a screening mammogram, i think i'm going to have a hard time recommending they don't get screened. >> couric: or at least wait until 50, right? >> exactly. >> couric: dr. jennifer ashton, thanks so much. now to another major health story tonight, this one involving two popular cholesterol-lowering drugs. about 30 million prescriptions were written for vytorin and zetia last year, generating $3.5 billion in sales. but tonight dr. jon lapook tells us about a new study that questions whether they actually prevent heart disease.